This invention relates to an apparatus and method for building pneumatic tires and particularly for feeding belt strips to the building drum and positioning them over a laminated carcass band. Pneumatic tires and particularly bias type pneumatic tires have been generally built in a "flat band" and subsequently expanded to the toric shape in the curing mold. In building such tires, the belt assembly and tire tread are applied directly over a laminated carcass portion while in a flat band. Illustrative of the art generally is the equipment and methods described in U.S. Pat. Nos. 2,614,951, 2,614,952, 3,171,769, 3,156,601 and 3,645,826, which are owned by the assignee of the present invention.
Pneumatic tires of the radial type, on the other hand, have been commerically built by the "toric match" method where the tire carcass, built in a flat band, is expanded to a toric shape before applying the belt assembly and the tire tread. In this process, the tread and belt assemblies are separately built on a second rotatable building drum. Equipment for making radial tires by such methods is described and claimed in U.S. Pat. No. 3,475,254, which is owned by the assignee of the present invention.
Whether built in a flat band or by the toric match method, difficulty has been encountered in avoiding structural irregularities in the tire assembly that can adversely affect performance. For example, the belt assembly may vary substantially as to symmetry about the circumferential centerline of the tire building drum and the tire carcass. Moreover, the belt strips may stretch and distort as they are applied over the rotating carcass band. The resulting pneumatic tire may possess structural variations around its circumference that could impair certain of its performance characteristics.
The present invention substantially reduces such problems in the assembly of the belt or breaker strips and provides means by which the belt assembly can be precision aligned relative to the circumferential centerline of the building drum without stretching and distortion.